AT&T has told the U.S. Congress that its customers agreed to host Carrier IQ tracking software on their cellphones in their contracts. You might recall that, after the scandal over warrentless surveillance broke in 2006, AT&T quietly changed their contract for internet service to say that it -- not its customers -- owns all the customers' internet records. Those concerned about privacy might consider whether AT&T merits their trust.

To play the devil's advocate, handset-based data may allow carriers to know when an antenna has unexpectedly poor reach or is utterly malfunctioning despite reporting a healthy status on automated tests.